Method of making a rigid-flex circuit board

Abstract

A rigid-flex circuit board includes a core substrate, a first outer conductive circuit layer, and a second outer conductive circuit layer. The core substrate includes a first base layer and a second base layer. A first conductive circuit layer is formed on a surface of the first base layer, and a second conductive circuit layer is formed on a surface of the second base layer. An insulating layer is located between the first base layer and the second base layer. The first conductive circuit layer and the second conductive circuit layer are embedded within the insulating layer. A portion of the core substrate located within the first opening and the second opening is defined as a flexible board section, and the portions of the core substrate located outside of the first opening and the second opening are defined as a hard board section.

What is claimed is: 
     
       1. A method of making a rigid-flex circuit board, the method comprising:
 providing a first base layer and a second base layer, coating a photosensitive material on a surface of the first base layer and on a surface of the second base layer, and exposing the photosensitive material to form a circuit pattern; 
 coating a conductive material on the exposed portions of the surface of both the first base layer and the second base layer, removing the photosensitive material outside of the conductive material, and solidifying the conductive material to form a first conductive circuit layer on the first base layer and a second conductive circuit layer on the second base layer; 
 providing an insulating layer and laminating the insulating layer between the first base layer and the second base layer to form a core substrate, the first conductive circuit layer and the second conductive circuit layer embedded within the insulating layer; 
 providing a first adhesive layer, the first adhesive layer defining a first opening, and laminating the first adhesive layer to an outer surface of the first base layer, the first adhesive layer located on a surface of the first base layer opposite to the first conductive circuit layer, the first base layer exposed through the first opening; 
 providing and laminating a first copper film on a surface of the first adhesive layer opposite to the first base layer, forming a first outer conductive circuit layer from the first copper film, the first copper film defining an opening aligned with the first opening; and 
 wherein a portion of the core substrate located within the first opening is defined as a flexible board section, and the portions of the core substrate located outside of the first opening are defined as a hard board section. 
 
     
     
       2. The method of  claim 1 , further comprising:
 providing a second adhesive layer, the second adhesive layer defining a second opening, laminating the second adhesive layer to an outer surface of the second base layer, the second adhesive layer located on a surface of the second base layer opposite to the second conductive circuit layer, and the second base layer exposed through the second opening; and 
 providing a second copper film, laminating the second copper film on a surface of the second adhesive layer opposite to the second substrate, and forming a second outer conductive circuit layer from the second copper film, the second copper film defining an opening aligned with the second opening. 
 
     
     
       3. The method of  claim 2 , wherein the first opening and the second opening are directly opposite each other across the first base layer and the second base layer. 
     
     
       4. The method of  claim 2 , further comprising:
 forming a solder mask layer on a surface of the first outer conductive circuit layer facing away from the core substrate; and 
 forming a solder mask layer on a surface of the second outer conductive circuit layer facing away from the core substrate. 
 
     
     
       5. The method of  claim 2 , wherein the first conductive circuit layer and the second conductive circuit layer are made of high-polymer material and metal particles. 
     
     
       6. The method of  claim 2 , wherein the first conductive circuit layer and the second conductive circuit layer are solidified by ultraviolet light.